Increasing tape velocity by dynamic switching

ABSTRACT

An apparatus for controlling an electric motor is provided. A plurality of switches is provided for controlling a direction of current through motor coils of the electric motor. A brushless motor control circuit is connected to each of the plurality of switches. Responsive to a request to adjust one of an angular velocity and an angular acceleration of the electric motor, the plurality of switches are activated to place the motor coils in a predetermined configuration to maximize torque or reduce a total back electromotive force (BEMF) from the motor coils.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to field of data tape transportdevices. The present invention specifically relates to backelectromotive force (“BEMF”) voltage reduction in a storage drive (e.g.,a tape drive).

2. Description of the Related Art

Magnetic tape provides a means for physically storing data. As anarchival medium, tape often comprises the only copy of the data. A tapedrive is used to store and retrieve data with respect to the magnetictape. An example of a tape drive is the IBM TotalStorage Enterprise TapeDrive 3592 manufactured by IBM Corporation. Tape drives are typicallyused in combination with an automated data storage library. For example,the IBM TotalStorage Enterprise Tape Library 3494 manufactured by IBMCorporation is an automated data storage library that may include one ormore tape drives and data storage media for storing data with respect tothe tape drives.

Tape drives frequently employ DC motors and feedback control systemswith motor drivers for operating the DC motors, to producewell-controlled motion parameters such as position, velocity, and tapetension. While the motors rotate, a back electromotive force (“BEMF”) isproduced by the tape drive electric motors. This BEMF voltage isproduced because the electric motors generate an opposing voltage whilerotating.

In tape drives such as the aforementioned IBM 3592 used in theEnterprise range, and the Linear Tape Open used in the mid-range, thecurrent tape linear velocity is limited by the tape reel's angularvelocity. The tape reel's angular velocity approaches a maximum when theBEMF produced by the reel motor approaches the voltage of the powersupply to the reel motors. Tape drives typically operate from +5 and +12V power supplies; therefore it is not possible to increase the powersupply voltage to increase the tape reel angular velocity. In light ofthe foregoing, a need exists for a mechanism by which tape reel angularvelocity may be increased in tape transport systems incorporating fixedpower supplies.

SUMMARY OF THE INVENTION

While it is not possible to increase power supply voltage to increasetape reel angular velocity in tape transport systems implementing afixed power supply, it is possible to decrease the BEMF and increase thetape reel angular velocity by reducing the torque constant and voltageconstant of the reel motor. Reducing the torque constant of the reelmotor decreases the tape reel angular acceleration, impactingperformance. The present invention discloses apparatus and methodembodiments of mechanisms to selectively either reduce the BEMF from thereel motor, therefore increasing the allowable tape reel angularvelocity for a fixed power supply voltage, or maintain a higher tapereel angular acceleration. By use of the following mechanism, either thetape linear velocity or tape linear acceleration may be selectivelyincreased relative to present implementations.

Accordingly, in one embodiment, by way of example only, an apparatus forcontrolling an electric motor is provided. A plurality of switches isprovided for controlling a direction of current through motor coils ofthe electric motor. A brushless motor control circuit is connected toeach of the plurality of switches. Responsive to a request to adjust oneof an angular velocity and an angular acceleration of the electricmotor, the plurality of switches are activated to place the motor coilsin a predetermined configuration to maximize torque or reduce a totalback electromotive force (BEMF) from the motor coils.

In an additional embodiment, again by way of example only, a method forcontrolling an electric motor is provided. A request is received toadjust one of an angular velocity and an angular acceleration of theelectric motor. A plurality of switches is activated for controlling adirection of current through motor coils of the electric motor. Theplurality of switches are activated to place the motor coils in apredetermined configuration to maximize torque or reduce a total backelectromotive force (BEMF) from the motor coils.

In still another embodiment, again by way of example only, a method forcontrolling the rate of movement of tape media in a tape storage drivehaving a fixed power supply voltage is provided. The tape storage driveincludes at least one tape reel driven by an electric motor having aplurality of motor coils. A request is received to adjust one of anangular velocity and an angular acceleration of the tape reel. Aplurality of switches is activated for controlling a direction ofcurrent through the motor coils. The plurality of switches are activatedto place the motor coils in a predetermined configuration to maximizetorque or reduce a total back electromotive force (BEMF) from the motorcoils.

In still another embodiment, again by way of example only, a method ofmanufacturing an apparatus for controlling an electric motor isprovided. A plurality of switches is provided for controlling adirection of current through motor coils of the electric motor. Abrushless motor control circuit is connected to each of the plurality ofswitches. Responsive to a request to adjust one of an angular velocityand an angular acceleration of the electric motor, the plurality ofswitches are activated to place the motor coils in a predeterminedconfiguration to maximize torque or reduce a total back electromotiveforce (BEMF) from the motor coils.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a diagram illustrating the tape path in a tape transportsystem;

FIG. 2 is a block diagram of a motor control or driver circuit;

FIG. 3 is a portion of control circuit;

FIG. 4 is a first embodiment of motor coils with velocity switches;

FIG. 5 is a second embodiment of motor coils with velocity switches; and

FIG. 6 is an exemplary flowchart for operation.

DETAILED DESCRIPTION OF THE DRAWINGS

The illustrated embodiments below provide mechanisms for increasingmaximum tape reel angular velocity by use of a motor control switchingcircuit. The motor control switching circuit reduces the total Back EMF(BEMF) produced by the reel motor by bypassing a portion of the motorcoils when high angular velocity is needed. Although bypassing a portionof the motor coils reduces the rotational acceleration capability of themotor because the torque constant of the motor is reduced in the effortto reduce the voltage constant of the motor, the motor control switchingcircuit is able to produce the necessary acceleration when needed byswitching in the previously bypassed motor coils.

FIG. 1 is a diagram illustrating the tape path of an exemplary tapetransport system 100. The tape transport system 100 illustrated in FIG.1 accepts a tape cartridge 102 containing first tape reel 104 on whichis wound a length of tape 106. The tape transport system 100 includes asecond tape reel 108, at least one tape head 110 and guide rollers 112.Tape head 110 may have Anisotropic Magneto-Resistive (AMR), GiantMagneto-Resistive (GMR), or Tunnel Magneto-Resistive (TMR) read elementsto read data and manufacturer written servo information from tape 106,and Thin Film (TF) write elements for writing data to tape 106. When thecartridge 102 is inserted into the tape transport system 100, the tape106 is automatically threaded around the rollers 112, across the tapehead 110 and onto the second tape reel 108.

Motors (not shown) operatively coupled to the reels 104 and 108 pull thetape 106 across the tape head 110 which reads/writes information to/fromthe tape in a known manner. The motors may also move the tape 106 fromone reel to another at high speed in fast forward and rewind operations.The motors may be directly coupled to first tape reel, 104 and secondtape reel, 108 or there may be a mechanical drive system between thereels and the motor(s). Whether directly coupled or coupled through amechanical drive system, the type of coupling determines a mechanicalrelationship between the motor(s) and the tape reels. The mechanicaldrive system could be for example, gears, belts, pulleys, clutches, etc.

All tape operations may occur with the tape 106 moving in eitherdirection. Thus, either first tape reel 104 or 108 may serve as thesupply reel or the take-up reel, depending upon the direction of thetape 106. In FIG. 1, the first tape reel 104 within the cartridge 102 isshown serving as the tape supply reel while the second tape reel 108 isshown serving as the take-up reel. In the following description, theterm “supply reel” refers to the reel operating as the supply reel atthe present time and the term “take up reel” refers to the reeloperating as the take-up reel at the present time. Moreover, the terms“supply motor” and “take-up motor” refer to the motors operativelycoupled to the supply and take-up reels, respectively. The type of tapetransport system 100 shown in FIG. 1 is for illustrative purposes onlyand the invention may be employed with other types of transport systems.

Typically, tape 106 moves at a constant linear velocity VTAPE acrosshead 110. Hence, as the radius of the outer wrap of tape R104 and R108,of reels 104 and 108, changes, the angular velocity W104 and W108 ofreels 104 and 108 also change, per equation (1). Also, as VTAPEincreases, such as during a high speed search, W104 and W108 increaseper the following relationship:W104*R104=W108*R108=VTAPE  (1)Per equation (1) above, as the radius of one reel shrinks to itsminimum, which is at beginning-of-tape (BOT) for reel 108 andend-of-tape (EOT) for reel 104, that is where the respective motor isspinning at its maximum angular velocity and generates the maximum BEMF.This maximum BEMF is further increased as VTAPE is increased from thenormal data I/O velocity to the high-speed search velocity. BEMF is theangular velocity W of a reel motor multiplied by the voltage constantKvoltage of the motor, which is equal to the torque constant Ktorque ofthe motor when SI (metric) units are employed. It is the enclosedinvention which reduces these two constants by using selective switchingto bypass motor coils, in order to reduce the BEMF:BEMF=Kvoltage*W  (2)

The rotational acceleration capability of the motor is reduced perequation (3) when selectively bypassing motor coils because the torqueconstant Ktorque of the motor is reduced at the same time that thevoltage constant Kvoltage is reduced. Reduction of the torque constantKtorque reduces the torque provided by the motor, and that torquedivided by the rotational inertia of the motor and tape reel gives therotational acceleration of the motor and tape reel, equation (4).However, these bypassed coils may be selectively re-engaged when thathigher acceleration (or deacceleration) is desired, preferably when theangular velocity of the motor is in the range which permits an increasein back EMF (BEMF).Torque=Ktorque*Motor_Current  (3).Rotational Acceleration=Torque/(Rotational Inertia of Motor+Reel)  (4).

FIG. 2 is a block diagram of a motor control or driver circuit 200 forbrushless DC motors coupled to the reels 104 and 108 for operation ofthe disclosed invention. A commutator 202 provides gate control for aset of power switches, such as FET switches 204, 205, 206, 207, 208 and209, which, in turn, connect/disconnect the motor windings 210, 212 and214 to/from a motor power supply 216 using switch 251. Sense resistor220, current sense 221, rectifier 222 and filter 223 provide currentsense signal 228 to current error amp and compensator 226.

Current error amp and compensator 226 compares current sense signal 228to current reference 227 and provides an error signal 229 to Pulse WidthModulation (PWM) modulator 224. Current error amp and compensator 226also provides servo loop compensation to ensure a stable feedback loopfor PWM modulator 224. Commutator 202 accepts hall sensor inputs HA, HB,HC from hall sensors 203A, 203B, and 203C, respectively. Commutator 202also accepts enable loop 230, Enable high velocity 231 which providesVelocity select input, PWM input 232 to control the reel motors 306 and308 (FIG. 3) using FET switches 204, 205, 206, 207, 208 and 209.Velocity switch output 235 controls velocity switches 410, 411, and 412(FIGS. 4, 5). PWM oscillator 225 also provides input to PWM 224.

FIG. 3 is an exemplary block diagram of a portion of the tape system 300in which the velocity switch system of the present invention may beincorporated. Motor driver circuits 200A and 200B are coupled to the tworeel motors 306 and 308, respectively. Reel motors 306 and 308, drivefirst tape reel 104 and second tape reel 108 respectively (FIG. 1). Hallsensors 304A and 304B are coupled to the two reel motors 306 and 308,respectively.

The output from hall sensors 304A and 304B are coupled to hall sensordetection logic 310. During normal servo operation hall sensor detectionlogic 310 decodes the output signals from hall sensors 304A and 304B toprovide motor rotation information for servo software 350. Hall sensordetection logic 310 may be implemented for example by software,firmware, hardware circuits (such as a field programmable gate array(FPGA) 314 as shown), a CPU, ASIC, etc., or a combination thereof. Servosoftware 350 processes the output from hall sensor detection logic 310using control system laws to produce primary motor control signals thatare transferred through motor assist ASIC (Application SpecificIntegrated Circuit) 355 and delivered to motor driver circuits 200A and200B. Motor assist ASIC 355 provides current control logic.

A description of the operation of servo control system for the two reelmotors 306 and 308 is given in application Ser. No. 10/223,967 entitled“Direction detection and count method for three channel commutationsensor, filed on Aug. 8, 2002, by the assignee of the present invention,of which is hereby incorporated by reference in its entirety.

Servo software 350 operates within the microcode section 325 of CPU 316.Other software components, including, host interface 330 and errorrecovery 335 also operate within the microcode section 325 of CPU 316.Host interface 330 provides communication between external hosts and CPU316. Error recovery 335 provides software procedures to enable CPU 316to direct operations to recover from errors that may occur duringoperation of the tape drive.

FIG. 4 shows a first embodiment of velocity control switches 410-412with motor coils 420-425. Switches 410, 411, and 412 are shown in aposition to enable serial connection of motor coils 420-425. Duringacceleration or deceleration, Velocity switch output 235 activates andcontrols velocity switches 410, 411, and 412 in a position to enableserial connection of motor coils 420-425. This provides the maximumtorque from reel motors 306 and 308.

During periods of higher velocity, Velocity switch output 235 controlsvelocity switches 410, 411, and 412 in a position to enable parallelconnection of motor coils 420-425. This provides the minimum BEMF toallow the maximum velocity from reel motors 306 and 308.

FIG. 5 shows a second embodiment of velocity control switches 510-512with motor coils 520-525. Switches 510, 511, and 512 are shown in aposition to enable serial connection of motor coils 520-525. Duringacceleration or deceleration, velocity switch output 235 controlsvelocity switches 510, 511, and 512 in a position to enable serialconnection of motor coils 520-525. This provides the maximum torque fromreel motors 306 and 308.

During periods of higher velocity, velocity switch output 235 controlsvelocity switches 510, 511, and 512 in a position to enable bypass ofmotor coils 520, 522, and 524 (coils 520, 522, and 524 are left open).This provides the minimum BEMF to allow the maximum velocity from reelmotors 306 and 308.

Turning to FIG. 6, an exemplary method of operation incorporating themechanisms of the present invention is depicted. As one skilled in theart will appreciate, various steps in the method may be implemented indiffering ways to suit a particular application. In addition, thedescribed method may be implemented by various means, such as hardware,software, firmware, or a combination thereof. For example, the methodmay be implemented, partially or wholly, as a computer program productincluding a computer-readable storage medium having computer-readableprogram code portions stored therein. The computer-readable storagemedium may include disk drives, flash memory, digital versatile disks(DVDs), compact disks (CDs), and other types of storage mediums.

FIG. 6 shows an exemplary flowchart 600 for operation. At step 605,control circuit 200 receives a command from a tape drive to change therotation of reel motors 306 and 308. If at step 608, the tape driverequires an accelerate mode of operation, then step 612 is executed toenable velocity control switches 510-512 for serial coil connection. Ifat step 608, the tape drive requires an accelerate mode of operation,then step 611 is executed to disable velocity control switches 510-512for serial coil connection.

Control flows from step 611 or 612 to step 615. At step 615, reel motors306 and 308 are stopped, then control flows to step 630 to end,otherwise control flows to step 610, to receive another command from thetape drive.

In certain embodiments, more than two motor coils per phase may be usedto provide multiple maximum velocities for a given motor and powersupplies. For conceptual purposes, the mechanisms of the presentinvention may be thought to be analogous to a transmission in a car. Forslower speeds and more torque (to provide greater acceleration) multiplemotor coils are electronically switched in like low gears of atransmission, such as all coils 520-525 being electrically engaged asshown in FIG. 5. For higher velocities, less coils are used to reducethe BEMF, similar to the higher gears in a transmission, such asselectively bypassing coils 520, 522, and/or 524 as shown in FIG. 5.

The mechanisms of the present invention may be adapted for a variety oftape transport systems including a variety of tape media and tapedrives, as one skilled in the art will anticipate. While one or moreembodiments of the present invention have been illustrated in detail,the skilled artisan will appreciate that modifications and adaptationsto those embodiments may be made without departing from the scope of thepresent invention as set forth in the following claims. For example,this same invention may be applied to hard disk drives and optical diskdrives, as both of which use DC motors to spin a disk and both of whichcould benefit from faster spinning disks to reduce latency times fordata I/O. Additionally, this invention may be applied to both opticaltape as well as magnetic tape.

What is claimed is:
 1. A system for controlling the rate of movement oftape media in a tape storage drive, the system comprising: a powersource; tape storage drive including at least one tape reel; a tape reelmotor having power supplied by the power source for driving the at leastone tape reel, the tape reel motor having a plurality of motor coils; afirst phase comprising: a first switch coupled to a first velocityswitch, a first coil coupled to the first switch, a second coil, and afirst node coupled between the first coil and the second coil, the firstnode further coupled to the first switch; a second phase comprising: asecond switch coupled to a second velocity switch, a third coil coupledto the second switch, a fourth coil, and a second node coupled betweenthe third coil and the fourth coil, the second node further coupled tothe second switch; a third phase comprising: a third switch coupled to athird velocity switch, a fifth coil coupled to the third switch, a sixthcoil, and a third node coupled between the fifth coil and the sixthcoil, the third node further coupled to the third switch; a fourth nodecoupled to the second coil, the fourth coil, and the sixth coil; a fifthnode coupled between the third switch and the fifth coil, wherein: acurrent is bi-directional through the first phase, the second phase, andthe third phase, the first switch, the second switch, and the thirdswitch are configured to selectively place the first phase, the secondphase, and the third phase in a first configuration to maximize tapereel motor torque or in a second configuration to reduce a total backelectromotive force (BEMF) from each tape reel motor coil; wherein: inthe first configuration, the first switch, the second switch, and thethird switch are selectively in a first position to place the firstcoil, the second coil, the third coil, the fourth coil, the fifth coil,and the sixth coil in a serial configuration to maximize the tape reelmotor torque, and in the second configuration, the first switch, thesecond switch, and the third switch are selectively in a second positionto place the first coil, the second coil, the third coil, the fourthcoil, the fifth coil, and the sixth coil in a parallel configuration toreduce the total BEMF and increase angular velocity in the first phase,the second phase, and the third phase.
 2. The system of claim 1, furthercomprising a controller coupled to the first switch, the second switchand the third switch, wherein the controller is configured to transmit arequest to adjust the angular velocity and an angular acceleration ofthe at least one tape reel, and the first switch, the second switch, andthe third switch are positioned to connect the first phase, the secondphase, and the third phase in the parallel configuration to reduce thetotal BEMF from the first coil, the second coil, the third coil, thefourth coil, the fifth coil, and the sixth coil to and allow for greaterangular velocity of the at least one tape reel.
 3. The system of claim1, further comprising a controller coupled to the first switch, thesecond switch and the third switch, wherein the controller is configuredto transmit a request to adjust the angular velocity and an angularacceleration of the least one tape reel and the first switch, the secondswitch, and the third switch are positioned to bypass an electricalconnection to at least one of the first coil, the second coil, the thirdcoil, the fourth coil, the fifth coil, and the sixth coil to provide aminimum back EMF and to maximize angular velocity.
 4. The system ofclaim 1, further comprising a controller coupled to the first switch,the second switch and the third switch, wherein the controller isconfigured to transmit a request to adjust the angular velocity and anangular acceleration of the least one tape reel to one of increase ordecrease the angular acceleration, and the first switch, the secondswitch, and the third switch are positioned to connect the first coil,the second coil, the third coil, the fourth coil, the fifth coil, andthe sixth coil in the serial configuration to maximize torque.
 5. Thesystem of claim 1, further comprising a controller coupled to the powersource, wherein the first switch, the second switch, and the thirdswitch are selectively activated by the controller to further place thetape storage drive in a third configuration and, in the thirdconfiguration, the first switch, the second switch, and the third switchare activated to place the first phase, the second phase, and the thirdphase in a bypass configuration to reduce a total back electromotiveforce (BEMF) from the first coil, the second coil, the third coil, thefourth coil, the fifth coil, and the sixth coil and to maximize angularvelocity.
 6. The system of claim 1, further comprising: a controllercoupled to the first switch, the second switch and the third switch; anda power inverter connected between the power source and the controller.7. The system of claim 1, wherein the power source is a battery.
 8. Acomputer program product using a processor device for controlling therate of movement of tape media in a tape storage drive having a fixedpower supply voltage, the tape storage drive including at least one tapereel driven by a tape reel motor having a plurality of motor coils, thecomputer program product comprising a least one non-transitorycomputer-readable storage medium comprising instructions that, whenexecuted, cause a system to: provide a first phase comprising a firstswitch coupled to a velocity switch, a first coil coupled to the firstswitch, a second coil, and a first node coupled between the first coiland the second coil, the first node further coupled to the first switch;provide a second phase comprising a second switch coupled to thevelocity switch, a third coil coupled to the second switch, a fourthcoil, and a second node coupled between the third coil and the fourthcoil, the second node further coupled to the second switch; provide athird phase comprising a third switch coupled to the velocity switch, afifth coil coupled to the third switch, a sixth coil, and a third nodecoupled between the fifth coil and the sixth coil, the third nodefurther coupled to the third switch; provide a fourth node coupled tothe second coil, the fourth coil, and the sixth coil; provide a fifthnode coupled between the third switch and the fifth coil; provide abi-directional current through the first phase, the second phase, andthe third phase; configure the first switch, the second switch, and thethird switch to selectively place the first phase, the second phase, andthe third phase in a first configuration to maximize tape reel motortorque or in a second configuration to reduce a total back electromotiveforce (BEMF) from each tape reel motor coil; wherein: in the firstconfiguration, the first switch, the second switch, and the third switchare selectively in a first position to place the first coil, the secondcoil, the third coil, the fourth coil, the fifth coil, and the sixthcoil in a serial configuration to maximize the tape reel motor torque,and in the second configuration, the first switch, the second switch,and the third switch are selectively in a second position to place thefirst coil, the second coil, the third coil, the fourth coil, the fifthcoil, and the sixth coil in a parallel configuration to reduce the totalBEMF and increase angular velocity in the first phase, the second phase,and the third phase.
 9. The computer-readable storage medium of claim 8,comprising further instructions that, when executed, cause a system totransmit a request to adjust the angular velocity and an angularacceleration of the at least one tape reel, and the first switch, thesecond switch, and the third switch are positioned to connect the firstphase, the second phase, and the third phase in the parallelconfiguration to reduce the total BEMF from the first coil, the secondcoil, the third coil, the fourth coil, the fifth coil, and the sixthcoil to and allow for greater angular velocity of the at least one tapereel.
 10. The computer-readable storage medium of claim 8, comprisingfurther instructions that, when executed, cause a system to transmit arequest to adjust the angular velocity and an angular acceleration ofthe least one tape reel and the first switch, the second switch, and thethird switch are positioned to bypass an electrical connection to atleast one of the first coil, the second coil, the third coil, the fourthcoil, the fifth coil, and the sixth coil to provide a minimum back EMFand to maximize angular velocity.
 11. An method, using a processordevice, for controlling the rate of movement of tape media in a tapestorage drive having a fixed power supply voltage, the tape storagedrive including at least one tape reel driven by a tape reel motorhaving a plurality of motor coils, the method comprising: providing afirst phase comprising a first switch coupled to a velocity switch, afirst coil coupled to the first switch, a second coil, and a first nodecoupled between the first coil and the second coil, the first nodefurther coupled to the first switch; providing a second phase comprisinga second switch coupled to the velocity switch, a third coil coupled tothe second switch, a fourth coil, and a second node coupled between thethird coil and the fourth coil, the second node further coupled to thesecond switch; providing a third phase comprising a third switch coupledto the velocity switch, a fifth coil coupled to the third switch, asixth coil, and a third node coupled between the fifth coil and thesixth coil, the third node further coupled to the third switch;providing a fourth node coupled to the second coil, the fourth coil, andthe sixth coil; providing a fifth node coupled between the third switchand the fifth coil; providing a bi-directional current through the firstphase, the second phase, and the third phase; and configuring the firstswitch, the second switch, and the third switch to selectively place thefirst phase, the second phase, and the third phase in a firstconfiguration to maximize tape reel motor torque or in a secondconfiguration to reduce a total back electromotive force (BEMF) fromeach tape reel motor coil; wherein: in the first configuration, thefirst switch, the second switch, and the third switch are selectively ina first position to place the first coil, the second coil, the thirdcoil, the fourth coil, the fifth coil, and the sixth coil in a serialconfiguration to maximize the tape reel motor torque, and in the secondconfiguration, the first switch, the second switch, and the third switchare selectively in a second position to place the first coil, the secondcoil, the third coil, the fourth coil, the fifth coil, and the sixthcoil in a parallel configuration to reduce the total BEMF and increaseangular velocity in the first phase, the second phase, and the thirdphase.
 12. The method of claim 11, further comprising transmitting arequest to adjust the angular velocity and an angular acceleration ofthe at least one tape reel, and the first switch, the second switch, andthe third switch are positioned to connect the first phase, the secondphase, and the third phase in the parallel configuration to reduce thetotal BEMF from the first coil, the second coil, the third coil, thefourth coil, the fifth coil, and the sixth coil to and allow for greaterangular velocity of the at least one tape reel.
 13. The method of claim11, further comprising transmitting a request to adjust the angularvelocity and an angular acceleration of the least one tape reel and thefirst switch, the second switch, and the third switch are positioned tobypass an electrical connection to at least one of the first coil, thesecond coil, the third coil, the fourth coil, the fifth coil, and thesixth coil to provide a minimum back EMF and to maximize angularvelocity.
 14. The method of claim 11, further comprising transmitting arequest to adjust the angular velocity and an angular acceleration ofthe least one tape reel to one of increase or decrease the angularacceleration, and the first switch, the second switch, and the thirdswitch are positioned to connect the first coil, the second coil, thethird coil, the fourth coil, the fifth coil, and the sixth coil in theserial configuration to maximize torque.
 15. The method of claim 11,further comprising selectively activating the first switch, the secondswitch, and the third switch to further place the tape storage drive ina third configuration and, in the third configuration, the first switch,the second switch, and the third switch are activated to place the firstphase, the second phase, and the third phase in a bypass configurationto reduce a total back electromotive force (BEMF) from the first coil,the second coil, the third coil, the fourth coil, the fifth coil, andthe sixth coil and to maximize angular velocity.